This invention generally relates to the production of polyunsaturated fatty acids, and more specifically to the production of 12-(S)-hydroxyeicosapentaenoic acid.
Polyunsaturated fatty acids possessing double bonds between the third and fourth carbon from the terminal methyl group (commonly known as W-3 fats) have been isolated in the tissues of fish. Tests conducted on these materials show considerable promise in the treatment of numerous diseases, including asthma, arteriosclerosis, heart disease, cancer, and various inflammatory conditions.
While many of the W-3 fats are structurally similar to each other, each may affect the human body in a different way. This has created a demand for a wide variety of W-3 fats for research purposes.
Originally, these materials were obtained by the chemical treatment of fish oils. Fish oils contain eicosapentaenoic acid (EPA) as a basic constituent, which is enzymatically treated to produce the desired product. However, this method is very expensive and time consuming.
Recent research has shown that certain polyunsaturated fatty acids and related derivatives may be isolated from other marine organisms, including algae. For example, Gunstone, F. D. in "Fatty Acids and Glycerides", Natural Product Reports, 95-113 (1987), discusses the isolation of many desired materials from algae. At page 95, the Gunstone article describes the isolation of ethyl (10Z,13Z)-hexadeca-10,13-dienoate from the brown alga Cystoseira barbata, and gamma-linolenic acid from the blue-green alga Microcystis aeruginosa.
Lopez, A. and Gerwick, W. H., in Lipids, Vol. 22, 190-194 (1987) disclose the isolation of two new fatty acid metabolites from the temperate red marine alga Ptilota filicina. These metabolites include 5(Z),7(E),9(E), 14(Z),17(Z)-icosapentaenoic acid and 5(E),7(E),9(E),14(Z), 17(Z)-icosapentaenoic acid. The structures of these new compounds, isolated as methyl ester derivatives, have been obtained from detailed nuclear magnetic resonance studies.
A variety of potentially antimicrobial materials have been isolated from the red alga Laurencia hybrida, as discussed in Higgs, M. D., "Antimicrobial Components of the Red Alga Laurencia hybrida (Rhodophyta, Rhodomelaceae)", Tetrahedron, Vol 37, 4255-4258 (1981). According to Higgs, two classes of halogenated metabolites have been isolated from Laurencia hybrida, including a series of C.sub.15 enyne ethers, and a group of halogenated sesquitepenes. Some of these materials have antimicrobial characteristics, while others appear to possess herbicidal activity against numerous broad-leafed plants.
In Higgs, M. D. and Mulheirn, L. J., "Hybridalactone, An Unusual Fatty Acid Metabolite From the Red Alga Laurencia Hybrida (Rhodophyta, Rhodomelaceae)", Tetrahedron, Vol 37, 4259-4262 (1981), extracts from the red alga Laurencia hybrida are again discussed. These extracts include 11-formyl-undeca5(Z),8(E),10(E)-trienoic acid which may possess antimicrobial properties.
Research involving sea urchin eggs is desribed in an article by Hawkins, D. J. and Brash, A. R., entitled "Eggs of the Sea Urchin, Strongylocentrotus purpuratus, Contain a Prominent (11R) and (12R) Lipoxygenase Activity", The Journal of Biological Chemistry, Vol. 262, 7629-7634 (1987). This article discusses the isolation from sea urchin eggs of a variety of compounds including (11R)-hydroxy-5,812,14-ZZEZ-eicosatetraenoic acid, (12R)-hydroxy-5,8,10,14-ZZEZ-eicosatetraenoic acid, and the (11R) and (12R)-hydroxy analogs of eicosapentaenoic acid.
Finally, an extensive discussion of algal nonisoprenoids is presented in Moore, R. E., Marine Natural Products, Chemical and Biological Perspectives, Academic Press, Vol. 1, pp 42-124 (1978). This reference involves a review of important chemical materials obtainable from algae. For example, the materials include those isolated from Aspargopsis taxiformis, an edible red alga from Hawaii. Almost 100 compounds have been isolated from this alga, as shown on pps. 61-63 of the reference. Also discussed on pps. 74-91 is the isolation of numerous lipid materials from a variety of forms of blue-green algae.
However, a practical method for isolating many of the potentially valuable fatty acid metabolites is still needed. One important material offering potential in the treatment of numerous diseases is 12-(S)-hydroxy-5(Z),8(Z),10(E),14(Z), 17(Z)-eicosapentaenoic acid (hereinafter designated as 12-(S)-HEPE). In addition to the treatment of diseases, radio-labeled 12-(S)-HEPE offers potential as an antibody-forming agent usable in radio amino assay kits designed to detect 12-(S)-HEPE in living tissue. At present, there is no practical and inexpensive method for producing this material. It has traditionally been manufactured by the enzymatic treatment of eicosapentaenoic acid (EPA) from fish oil to produce a complex mixture from which 12-(S)-HEPE is isolated.
Since a practical and inexpensive method for obtaining this chemical did not exist prior to the present invention, 12-(S)-HEPE has traditionally been expensive and available only in limited amounts.